1. Field of the Invention
This invention pertains to a reinforced chamber with a hollow cross section for windows, doors and similar structures.
2. Description of the Prior Art
In German Patent No. 87 14 076 (European Patent PS 0 312 646), a center support for synthetic window frames is disclosed, wherein the cross section of the insert includes two portions which are mirror images of each other and facing each other, each of which has the basic shape of a "U". The two portions are arranged with the base shanks abutting one another. Each base shank is provided with reinforcing fins extending in the longitudinal direction, spaced from each other and parallel to each other thereby forming two screw channels. The dimensions of the shank are chosen so that each portion of the insert can be inserted into the chamber with some "play". Screws are inserted into the screw channels to secure the portions tightly and eliminate the "play". Such an insert with two halves and with such a cross section which can be loosely inserted into the hollow chamber has a number of disadvantages. For example, the screw channels for the abutment screws are formed only after the two halves abut each other, that is, the reinforcing fins in the halves must form one upper and one lower screw channel, into which the screws can be inserted. However, if the height of the cross section of the hollow chamber has even minor dimensional variations, the reinforcing fins do not align exactly opposite each other and a screw channel is not formed. This requires additional installation effort to resolve this problem. Similarly, if the width of the cross section of the hollow chamber has even minor dimensional variations, the sections tilt and insertion of the screws is difficult. An additional disadvantage is that the sections with their head and foot groove, in order to be functional, must be supported on the inner wall of the cross section of the hollow chamber. After insertion of the screws, these grooves press into the plastic material which results in an inelastic deformation of the synthetic material and, eventually, in a loosening of the screws. Additionally, the assembly of the sections is cumbersome and time consuming. Moreover, in longer configurations, such an apparatus can tend to be noisy.
The chamber with a hollow cross section disclosed in German Patent No. PS 40 20 559 is equipped with a single reinforcement piece having a one-sided open screw channel and thereby eliminates many of the disadvantages of German Patent No. 87 14 076 discussed above, but is still disadvantageous in that external elements like metal fittings and the like cannot be connected to the reinforcement piece, which extends to about the center of the hollow chamber, but rather are connected to the wall (which is typically made of plastic or other synthetic material) of the hollow chamber. This causes a weak connection and stress on the wall.